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My friends Bob and Bev photographed this very faded, tattered female monarch flying around the milkweed plants in their backyard near the Museum last week. The butterfly is a migrant from Mexico, looking for places to lay her eggs as a last hurrah before she dies.

Detail of a healthy monarch’s wing

The monarch we found with faded, damaged wings

She must be very tired!

Last fall, she flew from somewhere in eastern North America all the way to central Mexico, where she spent the winter mostly in hibernation. A few weeks ago, she and the other overwintering butterflies, sensing the lengthening days and warming temperatures, left the shelter of the sanctuary’s trees and headed back north to complete the journey. They are just now getting to Texas.

This old girl’s eggs will hatch and — if they have enough milkweed — the caterpillars will mature and pupate. Then, when they emerge as adult butterflies, at least some of them will continue the journey north. By July, monarchs will have reached the northern limit of their range. These summer generations don’t live as long, and don’t travel nearly as far.

If you see worn and faded monarchs at this time of year, they are almost certainly migrants returning from their winter in Mexico. You can help them to fulfill their “purpose” by providing nectar for their last few meals, and more importantly, milkweed for the new generation. These returning migrants will only last a few days now that they’ve gotten here — they are on their last “wings” after nearly nine months of life, and at least 2,000 miles of travel.

The butterflies need your help! With urbanization, and a host of other factors, monarch butterflies are at risk of not finding places to lay their eggs. So why not help while improving the butterfly traffic through your garden with a butterfly-seducing plant from our biannual plant sale?

Milkweed plants in the genus Asclepias are extremely important for butterflies, especially monarchs. While the blooms provide copious amounts of nectar for many different butterflies, the foliage is an essential part of the monarch butterfly’s life cycle. Milkweeds are the only plant monarch caterpillars will eat. In other words, they can’t live without it!

Native milkweed plants grow along roadsides and in open fields. The butterflies find them by honing in on their volatile chemicals and finally locate the exact plant by “tasting” nearby plants with special receptors called chemoreceptors on their feet. Once a gravid female (one who has mated and is ready to lay eggs) finds a good milkweed plant, she will lay eggs on it — and the miraculous process of metamorphosis has begun!

There are about 100 species of Asclepias in the United States, and over 30 in Texas — but monarchs seem to prefer some of them over others. According to a study by Linda S. Rayor, described in The Monarch Butterfly: Biology and Conservation, when given a choice, monarchs prefer to lay eggs on other species of milkweed over the native species Asclepias tuberosa.

Besides being a host plant for Monarch larvae, Tropical Milkweed (A. curassavica) is a great nectar source for many butterfly species!

Why? Different Asclepias species contain different cardenolide concentrations (cardenolides are the chemicals in the milkweed leaves that taste bitter). As they eat, the caterpillars store these toxic chemicals in their bodies and thus become distasteful to their predators. A. tuberosa has been found to contain low amounts of cardenolides compared to most other species of milkweed. Although it is unclear how monarchs “know” this, they do not usually use A. tuberosa as a host plant.

Several other native milkweed species, however, are great host plants for the monarch. Asclepias asperula (Antelope Horns), A. viridis (Green Milkweed), A. incarnata (Swamp Milkweed) and A. oenotheroides (Zizotes Milkweed) are some of the more commonly found milkweed plants in our area that monarchs use as host plants.

Unfortunately, most of the native milkweeds are hard to find in plant nurseries. One reason is that their seeds require moist stratification to germinate, and even with this pretreatment, germination can be splotchy. Furthermore, young plants of A. asperula, viridis and oenotheroides take several seasons to establish their thick taproots, and can be hard to transplant.

On the bright side, most of the native milkweeds, except for A. incarnata, are drought tolerant and can handle being mowed. Swamp milkweed obviously likes moist soil. All milkweeds grow best in full sun.

Asclepias viridis, Green Milkweed

Most gardeners are familiar with tropical milkweed, or Asclepias curassavica. This plant is commonly available in local plant nurseries and attracts butterflies like a magnet! Its bright orange and gold flowers are irresistible to many butterflies, and the high levels of cardenolides in its foliage make it especially sought out by female monarchs looking for a place to lay their eggs. Although it originates in more tropical climes, it is relatively cold hardy and will usually come back from the base of the plant after a freeze. It is also easy to propagate from seed, and in fact will sometimes seed out (make more of itself) in a garden.

So tropical milkweed seems like the ideal plant. However, one issue with this species is that it is not native to our area and does not exhibit the same characteristics of our native milkweeds, all of which die back to the ground in winter. This perennial habit seems advantageous, but it can be a problem for a couple of reasons. Because it has leaves year-round, it may encourage monarchs to overwinter locally instead of migrating to Mexico. It can serve as a host for a disease that affects monarchs, called Ophryocystis elektroscirrha, or simply O.e. This disease is caused by a protozoan parasite and is spread in the dormant stage of its lifecycle as a tiny spore.

These spores are typically on the abdomen of an infected monarch butterfly and can be spread to her eggs or onto the milkweed plants themselves when a female lays eggs. Then, when the caterpillars hatch out of the eggs, they consume the spores that lie on their empty egg shells or on the leaves around the egg and become infected.

Over a few generations, the parasite load can build up to high enough levels that it impacts the butterfly’s survival. Depending on the severity of the infection, the disease can make the caterpillars look a bit grayish and their stripes not as distinct. When the caterpillars pupate, their chrysalis may look brownish or spotted. The butterfly inside may emerge but have problems, such as an enlarged, gray abdomen and weak, faded wings.

Sometimes they emerge and look healthy, but secretly harbor O.e. spores on their abdomens. Other times they don’t emerge from the chrysalis at all, or get stuck while trying to come out.

So what is my point? I thought we were talking about milkweed plants! The reason this is important is because O.e. spores persist on the leaves of the tropical milkweed plants, waiting for an unsuspecting caterpillar to munch them up. To break this cycle, we recommend cutting your tropical milkweed plants back after a monarch generation has stripped their leaves, especially in the spring and fall. A simple pruning of the plant’s stems about six inches from the ground will get rid of any remaining spores and will sprout new growth in no time.

Some other closely related plants that monarchs will use as a host are Gomphocarpus physocarpus or “family jewels” milkweed, and a species of Funastrum or twinevine. Gomphocarpus is a lot like A. curassavica in that it doesn’t lose its leaves in the winter so it also needs to be cut back periodically to keep it from spreading O.e.

Funastrum cynanchoidies flower

Funastrum or twinevine is an interesting climbing plant native to south Texas and Mexico. The plant is not very impressive looking until the summer, when it puts on beautiful balls of milkweed-like flowers that are great nectar sources for many kinds of butterfly. Another good thing about it is that when monarch caterpillars have stripped all your milkweed plants of their leaves and are still hungry, they will eat the leaves of Funastrum.

With their habitat dwindling due to urbanization, the use of Round Up ready crops, shrinking right-of-ways due to intensive agricultural practices and other factors, monarch butterflies need all the help they can get. The take-home message today is PLANT MORE MILKWEED! (please)

Spring-time is almost here and the butterflies will soon be fluttering all around town. I have actually seen a lot already, but we do live in Texas, so that’s not a surprise. Since I work in an exotic butterfly house, I definitely have my favorite exotic butterflies, but I also have a few favorites that are here in Texas as well. Many of you may be expecting me to write about the monarch, Danaus plexippus, but I thought I would write about some different, but still very common ones that we find around here in Houston. If you are interested in monarchs, please check out Nancy’s blog - all about monarch migration.

The Gulf Fritillary,Agraulis vanillae, is a butterfly that frequents Houston quite often.Its caterpillars feed off of every single part of the passion vine plant, which make them poisonous and nasty-tasting to predators.

A couple of summers ago, I had tons of these caterpillars on my passion vine plant. The caterpillars have large spines along their body with an underlying bold purple, orange, and black coloration, serving to warn predators of their danger!I’m sure many of you have seen this bright orange and black butterfly fluttering around nectar plants such as Lantana, Zinnia, Coneflowers, Butterfly Bush, and many others.

One of the most distinct characteristics of the Gulf Fritillary is the spectacular silvery, almost mirror looking, spots on the underside of the wings.The males and females look very similar, but the black stripes on upper side of the female’s wings are thicker and more pronounced.Although this butterfly is not here in the Butterfly Center very often, take advantage of its beauty outdoors right here in Houston.The goldrim butterfly, Battus polydamas, is a member of the swallowtail family (Papilionidae), but it does not have the typical tails that many of these butterflies have.The name ‘gold rim’ comes from the golden-yellow crescent shaped markings on the upper edges of both the fore and hind wing.Caterpillars of this species are gregarious (living together) in the early stages but become solitary when older. The caterpillars are a dark reddish gray color with paired fleshy tubercles along the back of the body.

I am very fond of these cute caterpillars and was fortunate enough to take this adorable picture in our butterfly garden right outside of the museum.Adults are mainly associated with disturbed areas of the forest and can be seen visiting gardens throughout the city.They are nectar feeders and especially like Lantana.Like many swallowtails, this butterfly flutters constantly while feeding instead of stopping to rest.This butterfly is fairly common in Florida and South Texas and will at times stray to Kentucky and Missouri.

Once spring-time hits, I seem to see this next butterfly all the time! As a native of heavily populated areas such as parks, yards, gardens, and road edges, the cloudless sulphur, Phoebis sennae, can be seen almost anywhere along the gulf coastal states. It is characterized by its pure bright yellow to greenish-yellow wings. The males use strong rapid flight to search for a receptive female. The eggs are laid singly on leaves of Cassia,which the caterpillars happily consume, and hide underneath, to rest. The pupae are oddly shaped, compressed from side to side with a greatly distended “chest and belly”. They use a silken girdle to attach themselves to the leaf during pupation. These butterflies are harmless to plant life and are a welcome visitor to any garden.

One of the largest butterflies that I see around town is the Giant Swallowtail, Papilio cresphontes. This fantastic butterfly is native to large portions of North, Central, and South America. It very common in Houston and can be seen gracefully fluttering and sipping the sweet nectar of flowers such as Lantana, Azalea, and Honeysuckle.

Characterized by the striking diagonal yellow band across its forewing, and its long yellow-filled tails, this butterfly is a joy to see in one’s garden! The larvae feed strictly on citrus plants and are commonly called “orange dogs.” As a defense, they cleverly disguise themselves as bird droppings as they sit motionless during the day and feed at night. As with other swallowtails, these caterpillars’ posses a bright reddish orange, y-shaped gland called an osmeterium, which contains a mixture of highly noxious chemicals that smell like rancid butter. This gland helps to protect the caterpillar from small predators such as ants and spiders. The pupal stage remains inconspicuous, resembling a piece of tree bark.

These four butterflies are only a few of the wonderful butterflies that live in Houston. If you are more interested in butterflies you should check out Butterflies of Houston & Southeast Texasby John and Gloria Tveten. It’s a wonderful book and has amazing pictures.

A universal favorite, most people know that these showy orange and black butterflies fly south every year to spend the winter in Mexico. Many of you may have raised their black, yellow, and white caterpillars on Mexican milkweed as a class project or in your backyard.

But why do the adult butterflies migrate, and how do they get there and back? Who are the people and cultures they encounter as they traverse the continent from north to south each year? How did we learn about their migration, and what does it tell us about the natural world?

To answer these questions, and to see some amazing footage of millions of butterflies in flight and at their overwintering grounds, be sure to watch NOVA’s long-awaited special, “The Incredible Journey of the Monarchs.” It airs on PBS tomorrow night (Tuesday, January 27) at 7 p.m.

Inspired by Sue Halpern’s book, “Four Wings and a Prayer,” the filmmaker followed the butterflies in hot air balloons and high tech gliders, interviewing researchers and ordinary citizens in Canada, the USA, and Mexico to tell the story of these unusual butterflies and the unique phenomenon of their migration.